This invention relates to items or components of installations or machines in static or dynamic contact with fluid. More particularly, the present invention relates to components of turbomachines flown or enveloped by fluid and to the components necessary for the supply and removal of fluid (working medium). The present invention covers the combination of essential features of the design of openings in said components and the application of advanced manufacturing methods for the realization of such openings.
The aerodynamic efficiency of turbomachines and machine components is determined by the growth and the separation of boundary layers forming along the wetted surfaces of the flow path.
In turbomachines, this applies to the surfaces of the blading and the surfaces of all hub and casing components. The boundary layers can be favorably influenced by the removal or supply of fluid at aerodynamically critical locations. Fluid removal and fluid supply requires the provision of openings in the surfaces of the blade and/or the hub and casing walls wetted by the main flow. These openings, hereinafter referred to as “secondary fluid ducts” (SFK), usually connect to a chamber which is flown by small secondary fluid quantities and is provided within the hollow-type blade or within the hub or casing. Openings with simple shapes according to the state of the art and producible according to the state of the art perform inaccurately and employ excessive secondary fluid quantities and are, therefore, not sufficiently efficient.
In order to obtain high efficiency of said SFK, a geometrically complex shape with high accuracy requirements must be adopted which are not, or not fully, producible with conventional cutting or forming methods. This applies, for example, if a SFK is employed to provide an accurate supply of secondary fluid to the main flow to stabilize the respective boundary layer and to guide this secondary fluid closely along the surface concerned.
The state of the art is disadvantageous in that the openings in items or components of installations or machines with complex shape, orientation and contour accuracy are not producible by conventional cutting processes. This applies, In particular, if the entirety of contours to be generated is not totally producible from one side of the item.
The cross-section of a SFK in components of turbomachines can, for example, have the shape of a curved nozzle. Reasons for the inability of the state of the art to provide the quality required of the SFK are its small size and its frequently oblique or curved orientation within the surrounding material.